Jesse c



entre etarras ramena JESSE C. KING, 0F. MGNTREAL, QUEBEC, CANAD.

stnc'rnonn.

Specification of Letters Patent. v

To all whom. it may concern:

Be it known that l, JESSE C. KING, a citizen of the United States, and resident of the city of Montreal, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Electrodes,l of which the vfollowing is a full,` clear, and exact description.

This invention relates to improvements in electrodes for use in electric' furnaces and the like.

It is well known that electrodes which usually consist of carbon waste or burn away quite rapidly at points remote from the active end, thus reducing the efficiency and lite of the electrode. rhe carbon body becomes heated to very high temperatures for a considerable distance back from the end, and

this heating renders the carbon more or less readily combinable with oxygen of the air or with other gases, with the result that the electrode burns away, thus reducing the sectional area and consequently altering the resistance and conductivity of the electrode.

Tleg mei nbfnrt ni? mv invention vis to provideV :n electrode having on the outer surface thereof a thin coating of non-oxidizing material designed to protect the body of the electrode from combination with gases at all parts of the surface not in actualoperation: I have found that a. coating of finely ground dolomite is very suitable for this purpose, and the coating may be applied in the manner described in my copending applicationQSerial No. 99,104, iled May 22nd, 1916. After the application ofthe protective coating, the electrode is preferably baked, so that the core and the coating become for all practical purposes integral.

Referring to the drawing, which represents a cross sectional view vof the electrode with the coating appliedthereto, 11 designates the core or electrode proper of carbon l having the surface 12 roughened by any suitable means. The coating o dolomite 13 is then applied' to the roughened surface, preferably in a plastic condition The electrode is then baked to drive cti the moisture and gases, and to harden both the coreand the coating.

'manner as possi me.'

The dolomite which is ground to a suitable inencss may be molded, pasted, y

pressed or sprayed on to the'roughened carbon core, and when suitably hardened, this coating forms an impenetrable coating between the electrode and the gases o the furnace.

lt is to be understood that the dolomite may include various proportions of lime;

for instance, some varieties of dolomite may contain 30% or higher of lime,.while other varieties may -contain less than 10% oi? lime.

lt may be found desirable to use a binder consisting of a carbonaceous material such as pitch or the oxids'of metals, such as calcium oxid or magnesium oxid, to hold the coating together during the baking process until it becomes thoroughly hardened.

If it is desired vto mold the surface coat-ing v onto the carbon electrode, the latter may be used in a suitable mold as a core and the surface coating may be pressed into the mold around the core in the usual manner."

It the surface coating is to be pasted onto the core, a trowel or other suitable implement may be used and this surface coating in plastic condition may be pasted onto the roughened surrace-oi Lne core, in as eac.. a l 'lo spray the coating onto the core, any suitable implement such as a cement gun may be employed.

Having thus described my invention, what I claim is 1. A coating for electrodes consisting of finely ground dolomite. 2. coating for electrodes, consisting of ,nely ground dolomite and'a carbonaceous fbinder for same.

, 3. An electrode havinga coating of dolomite bonded or baked on to the core.

4. An electrode-comprising a carbon core, having a. roughened surface, and a coating of dolomite bonded on to the roughened surface.

5. An electrode comprising a carbon core having a roughened surface, and a coating of dolomite mixed with a carbonaceous binding material bonded or baked on to the `roughened surface.

ln Witness whereof, l have hereunto setY my hand.-

' JESSE c. Kme.

, 1 Patented Aug. 5, rais; 

